Could patients with chronic obstructive pulmonary disease benefit from renin angiotensin system inhibitors? A meta-analysis

BACKGROUND: Chronic obstructive pulmonary disease (COPD) is considered related to chronic systemic inflammation. Renin angiotensin system (RAS) inhibitor, exerting an anti-inflammatory action in many systems, has been demonstrated relevant to the pathogenesis of COPD. However, the association between RAS inhibitor use and prognosis of patients with COPD remains controversial. Therefore, we conducted a meta-analysis and systematic review to summarise current evidence. MATERIAL AND METHODS: Databases, including Medline, Embase, Web of Science and Cochran Library, were searched for eligible studies by the end of 30 September 2022. Observational studies or randomised controlled trials (RCTs) that investigated the association of RAS inhibitor use with prognosis of COPD (mortality or risk of acute exacerbation) were selected. The Newcastle-Ottawa Scale was used for quality assessment of observational studies, while the Cochrane risk-of-bias tool was used to assess the quality of RCTs. Statistical analyses were performed using Stata V.15. We selected relative risk (RR) with 95% CI as the effect measure. Heterogeneity was assessed by I-squared (I(2)) statistics. The funnel plot was used for visual assessment of publication bias. RESULTS: A total of 20 studies with 5 51 649 subjects were included in the meta-analysis. The overall analysis indicated that RAS inhibitor use decreased the risk of death in patients with COPD (RR: 0.69, 95% CI: 0.61 to 0.78). Subgroup analyses were conducted according to comorbidities, race and type of RAS inhibitors, and the results kept consistent. However, in the pooled analysis of prospective studies, RAS inhibitor use did not significantly decrease the mortality (RR: 0.89, 95% CI: 0.78 to 1.02). Additionally, the risk of exacerbations of COPD did not decrease in patients who were prescribed RAS inhibitors (RR: 0.99, 95% CI: 0.80 to 1.23). The funnel plot indicated significant publication bias. CONCLUSION: RAS inhibitor use seemed to be associated with a reduction of mortality in patients with COPD. However, the available evidence is weak due to potential biases from retrospective studies and the heterogeneity across included studies.